In the machining of an object such as a metal mold, once a design change occurs after the metal mold was made, it is general that the deposition is carried out for shortage portions of the material in the metal mold, and, by using Computer Aided Design (CAD) data after the design change, the machining is carried out for the changed portions by a Numerical Control (NC) machine or the like. Incidentally, because the material used for the deposition in the metal mold machining have high hardness, compared with the machining the base material such as cast, it takes time of several times to machine the portion at which the deposition was carried out.
On the other hand, when the deposition was carried out, because it was not accurately known how much amount of deposition should be carried out to what portions, the deposition with a lot of margin including a cutting allowance (also called cutting margin), that is, the deposition with too large margin was carried out. Therefore, the waste of the deposition material and machining time after the deposition occurred.